8342936: Enhance java.io.IO with parameter-less println() and readln()

Reviewed-by: asotona, jpai, naoto

src/java.base/share/classes/java/io/ProxyingConsole.java

@@ -117,6 +117,18 @@ final class ProxyingConsole extends Console {
         }
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @throws IOError {@inheritDoc}
+     */
+    @Override
+    public String readln() {
+        synchronized (readLock) {
+            return delegate.readln();
+        }
+    }
+
     /**
      * {@inheritDoc}
      */